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You know, climate change is a problem. I once heard an argument against the burning of fossil fuels on the grounds that Earth would become like Venus. And we all know what sort of place Venus is. It’s interesting to think that Mars and Venus are completely opposite in terms of climate and atmospheric conditions, though an article in this month’s Scientific American points out that it’s possible that Mars’s rarefied atmosphere and Venus’s CO2 insulated greenhouse might have been created by some very similar processes. At the very least, they are both the result of a net loss of gases from their respective atmospheres. The crazy thing the article points out is that eventually Earth is more likely to end up like Venus than Mars. A scorching desert with rivers of molten lead.

Did you know that our atmosphere leaks three kilograms of hydrogen each second? It’s the lightest gas and so it concentrates in the upper atmosphere and just sort of evaporates off, disappearing into space. I did some further research and discovered that all atmospheres are constantly evaporating. Even the Sun is losing mass constantly. Ever consider what the solar wind might consist of? It’s material that’s being ejected off the surface of the sun. Our sun will lose probably .01 percent of its mass from evaporation throughout its main sequence, but there are larger suns that slough off some forty percent of their mass just from generating solar wind.

What I mean to say is, the universe is always in a constant state of flux. Everything is changing constantly. It’s the only thing that’s constant. In accordance with the second law of thermodynamics, that flux always tends towards a greater state of disorder or less potential energy.

Let’s say we stopped belching greenhouse gases into the atmosphere. What would happen? Slowly, over time–about a billion years–the sun is going to get brighter as its main sequence continues. This means that water vapor will not condense and rain back to the Earth’s surface as readily. This will allow that water vapor to decay into hydrogen and oxygen under the force of a brighter sun’s ultraviolet radiation. After another billion years, our oceans will have all dried up and our atmosphere will have a much higher concentration carbon dioxide as hydrogen and oxygen leach off into the ether. Earth becomes another Venus. And that’s it. Earth is finished. Two billion years.

This came as something of a shock to me. I’ve always thought that life on Earth was dependent on the sun continuing to give off energy, feeding our biological economy. I never considered the possibility that the sun itself might be our undoing. I had never thought about our own atmosphere backfiring on us. The sun’s main sequence will last another seven billion years. That’s a lot of time. But if Earth is only habitable for another two, we’ve essentially got a third of that to…what?

I always thought it would be possible that humans might still exist on Earth in three billion years when the Milky Way crashes into Andromeda. I always thought there was a remote possibility (depending, of course, on our own ability to wise up). But there is no such possibility. Two billion years is a very small amount of time, cosmically speaking. But even beyond that event, what is there? Perhaps we find other habitable planets and generate the necessary technology to colonize them?

If the universe is expanding–which may or may not be the case–the second law of thermodynamics means that eventually the entire universe will be cold, lifeless, and dark. When? In a trillion years, our local galaxy cluster will have merged into one huge galaxy. Another trillion years later (again, continuing to assume the existence of dark energy), all other galaxies will have red shifted to the such an extent that they will no longer be detectable.

Star formation ceases at around 100 trillion years.

Slowly, all matter in the universe will be absorbed into black holes. But even black holes do not last forever. Slowly they decay. 10100 years from now, the last of the black holes will have evaporated to nothing, the tiny particles that they kicked off having dispersed throughout the eternity of space. Then comes the Dark Era.

And this is the thing that gets me. There is going to be crazy shit happening in the universe so long after our two billion years is up, and Earth won’t be here. At least, there won’t be anything worth calling life on Earth to experience it. All we have is these two billion years. So what do we do? It would be nice if we could do as much in that two billion years as possible.

I could turn this into a stump speech for renewable resources, etc. But you’ve heard it all before. I just wanted to put some shit into perspective.